In a conventional electric motor device, many electronic parts, such as transistors and other semiconductor elements, resistors and capacitors, are coupled together and mounted on a wiring pattern of a printed circuit board as exemplified in the patent document (JP 2002-345211A).
According to the patent document, for example, six switching elements are provided and selectively turned on or off to control the conduction timing of coil currents supplied to three-phase coils. This forms a rotating magnetic field for the purpose of driving a brushless motor. These switching elements are formed as a plurality of independent semiconductor modules. The semiconductor modules are linked together and mounted on the conductive wiring pattern of the printed circuit board.